Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare this safe read-only and closed-world, so the description is free to add the more useful detail: the returned opaque id is unique within the app and stable across token refresh, reconnection, and display-metadata changes. That stability guarantee is real behavioral context not present in the annotations.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with what is returned and then the one non-obvious property (id stability). No filler, no restatement of the name.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a zero-parameter read with no output schema, the description supplies enough: what is returned (the caller's profile) and what the id means. It stops short of describing the profile's fields, which an agent may want, but the essential contract is covered.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so there is nothing for the description to disambiguate; baseline 4 applies. The description correctly frames the input as implicit (the request's credential context) rather than a callable argument.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Return the profile') and scopes it precisely to 'this request's authenticated credentials', which distinguishes it from the contract-oriented siblings. It does not name a sibling explicitly, but the identity/credential framing makes the distinct role obvious.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: the tool is for discovering who the caller is via their authenticated credentials. There is no explicit when-to-use/when-not guidance and no alternatives are named among the siblings (archetypes, get_contract, score_contract, etc.).

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.